A protein molecular weight marker or protein ladder can be used to identify the approximate size (molecular weight) or mass (amount) of a protein resolved by gel electrophoresis. As is recognized by those skilled in the art, the migration rate of a protein through a gel is inversely proportional to the protein's molecular weight.
There is a need in the field for protein ladders that can be visibly, fluorescently and chemiluminescently detected either simultaneously or sequentially. Additionally, simpler methods are needed for chemiluminescent systems that eliminate the need for the inclusion of antibodies with a catalytic function label to develop a chemiluminescence system.
Moreover, there is a need for improved methods of labeling a protein mixture, wherein the proteins are conjugated to multiple chemical moieties. The present invention satisfies these needs and provides other advantages as well.